Comparative Studies on Structural, Microstructural, and Dielectric Behavior of Ni 0.3 Zn 0.7 Fe 2-x R x O4 (0.00 < x < 0.25 & R = In/Cr) Spinel Ferrites for High Frequency Applications

Indium (In) and chromium (Cr) doped nickel zinc ferrites with chemical formula, Ni 0.3 Zn 0.7 Fe 2- x R x O 4 (0.00 < x < 0.25 & R = In/Cr) were synthesized by conventional solid state reaction method. X-ray diffraction data confirm the single phase cubic spinel structures in both the series of samples. The microstructures of In substituted samples are characterized by relatively larger grains with less rounded interfaces comparing to Cr doped samples. Dielectric studies reveal the existing of typical space charge polarization in both the series of the samples at higher frequencies. There observed significant variation in the magnitudes of the dielectric constant and loss tangent, the same were attributed to the possible size differences in the substituted ions correspond to different hopping mechanisms and thus display diverse dielectric behavior. All possible reasons for the variations in structural, microstructural and dielectric behavior observed in both the series were well explained in terms of their corresponding difference in their ionic radii, cationic preferences by the doped ions and possible conduction mechanisms.